A Highly Stable, New Electrochromic Polymer: Poly(1,4-bis(2-(3′,4′-ethylenedioxy) thienyl)-2-methoxy-5-2″-ethylhexyloxybenzene)

Authors


  • We gratefully acknowledge financial support from the Air Force Office of Scientific Research through F49620-00-1-0103 and the Army Research Office through MURI DAAD19-99-1-0316.

Abstract

A highly stable new electrochromic polymer, poly(1,4-bis(2-(3′,4′-ethylenedioxy)thienyl)-2-methoxy-5-2″-ethylhexyloxybenzene) (P(BEDOT-MEHB)) was synthesized and its electrochemical and electrochromic properties are reported. P(BEDOT-MEHB) showed a very well defined electrochemistry with a relatively low oxidation potential of the monomer at + 0.44 V versus Ag/Ag+, E1/2 at – 0.35 V versus Ag/Ag+ and stability to long-term switching up to 5000 cycles. A high level of stability to over-oxidation has also been observed as this material shows limited degradation of its electroactivity at potentials 1.4 V above its half-wave potential. Spectroelectrochemistry showed that the absorbance of the π–π* transition in the neutral state is blue-shifted compared to PEDOT, displaying a maximum at 538 nm (onset at 640 nm), thus giving an almost colorless, highly transparent oxidized polymer with a bandgap of 1.95 eV. Different colors observed at different oxidation levels and strong absorption in the near-IR make this polymer a good candidate for several applications.

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